A Comparative Study to Evaluate the Interplay of Lipoprotein (a) With Traditional Lipid Parameters in Overt and Subclinical Hypothyroidism

Abstract

Aims: In conjunction with triglyceride (TG) and HDLc, changes in the Lp (a) level in hypothyroidism have shown variable results. In the present study we made an effort to evaluate the role of Lp(a) as cardiovascular risk factor in both subclinical(SH) and overt hypothyroidism(OH) along with its dependence with dyslipidemic changes found in both groups. Study Design: It was a cross sectional, observational, non interventional, hospital based study Place and Duration of the Study: The study period was one year spanning a duration from February 2014 to January 2015 in the Dept. of Biochemistry, Calcutta National Medical College, Kolkata. Methodology: We evaluated the changes in Lp(a) TG, HDLc and fT4 levels in 30 overt and 34 subclinical hypothyroid patients and compared them with 34 control subjects in a hospital based cross-sectional study. Data were compared for difference between mean values and obtaining dependence of Lp(a) on lipid parameters. Results: Mean values of Lp(a), TG, TC and LDLc were found to be increased most in the OH group followed by that in the SH patients, the difference between two groups being significant statistically (p < 0.001). In contrast, fT4 and HDLc showed decreased levels in both SH and OH groups with a significant difference between them. Results of multiple linear regression analysis revealed that changes in the Lp(a) levels showed significant positive and negative dependence on the TG (β = 0.377 for OH and  0.296 for SH), and fT4 (β= -0.699 for OH and -0.380 for SH) and HDLc (β= -0.341 for OH and -0.393 for SH) respectively. Conclusion: Dyslipidemic features are evident in patients with SH as well as in the OH group that play also an important predictive role on the changes in Lp(a), indicating that in addition to traditional dyslipidemia, nontraditional risk factors like Lp (a) play a major role in initiating cardiovascular adverse events even in the early stages of hypothyroidism (SH).